Apparatus for pulverizing materials



Aug. 6, 1929. w. T. DOYLE 1,723,726

APPARATUS FOR PULVERIZING MATERIALS Filed Nov, 19, 1928 2 Sheets-Sheet 1INVENTOR I h i'llzam 1? Doyle A TT ORNE Y W. T. DOYLE Aug. 6, 1929.

APPARATUS FOR PULVERIZING MATERIALS Filed Nov, 19, 1928 2 Sheets-Sheetm'lliam 1' Doyle BY INVENTOR ATTORNEY Patented Aug. 6, 1929.

UNITED STATES PATENT OFFICE.

WILLIAM T. DOYLE, OF i BOSTOI\ T, MASSACHUSETTS, ASSIGNOR TO STURTEVANTMILL GOMPALIY, 031 BOSTON, MASSACHUSETTS, ACORPORATION OF.MASSACHUSETTS.

APPARATUS FOR PULVERIZING- MATERIALS.

Application riled. November 19, 1928. Serial No. 320,306.

The invention to be hereinafter described relates to apparatusforreducing materials. Many natural and manufactured materials varyiii-their degree of hardness, and of course, the harder the material,the more difiicult it is to grind. A grinding machine for maximumefficiency should have a uniform rate of feed of material to themachine, uniform fineness ofthe ground product, and maximum Output.However, owing to the varying degree of hardness of the material, it isusually necessary to vary'the rate of feed'of material tothe machine.Grinding machines are equipped with various types'of feeders, butusually theyare not capable of nicety of regulation, and-consequentlyvariations in the feed are objectionably large.

In machines requiring a short time for re,- ducing material, increase inthe rate of re ducing the material is rapid and can be promptlyobserved, but in machines requiring a long time for reducing material,such asare employed for high tonnages, increase in the rate of reducingthe material is on such a large scale that it has been founddifficult'to regulate. a p The purpose of the present invention,therefore, is to provide means to regulate the feed of unground materialto the mill auto-.

the material being ground, The regulation is such that on increase inhardness of material above normal, the speed of the feeding will bearrested, and on decrease in hardstarted or its speed will be increased,to the end that the material may be reduced by. the mill with uniformfineness of product and with maximum output.

In carrying the invention into.practical effect, in the present instancethere is provided a ball tube mill having plural compartments in whichstages of reduction of the material occur. The material to be reduced isfed into one end of the mill, and, the ground material is delivered fromthe opposite end of the mill and conveyed to a separator which may be anair or a screen separator. The tailings delivered by the separator arereturned to the mill for further reduction.

the regulation devices thereof; and

matically in response to the frangibility of means will be reduced, orthe feeding means ness of material, the feeding means will be It isimportant that the compartments of the mill shall not be overloaded withmaterial, since excess material in a compartment Wlll prevent the ballsfrom having their dc sired grinding effect. Another purpose of theinvention, therefore, is to provide means to prevent overloading of thecompartments,

Fig. 2 is a'vertical section taken on the line 2 2 ofFig. 1;

Fig. 3 on an enlarged scale is a side elevation of portionso'f'the chuteand showing Fig. 4 is a vertical section through chutes.

Referring to the drawings, the apparatus shown therein as one good formof the invention, comprises a ball tube mill 1 (Fi 1) comprising a rotartube having hea s the in the accompanying drawings,

3 and 5 at opposite enc s thereof. The head I 3 has a hollow trunnionjournalled in a hearing 7 11.

pier 15 on the foundation.

The tube contains a primary reducing compartment in the end portion 17,and a secondary reducing compartment in the end portion 19 thereof.These compartments have linings and contain suitable reducing mediawhich may be in the form of balls or other elements. The halls in theprimary reducing compartment are larger than those in the secondaryreducing compartment. Between these compartments in a division plate forautomatically transferring material reduced in the primary com artmentto the secondary compartment. ince the mounted on a pier 9 onthe-foundation The head 5' has a hollow-trunnion 1ournalled in a bearing13 mounted on a tor 33.

internal construction of this ball tube mill is usual and understoodin-the art, it is unnecessary to show and describe the same in detailherein.

Mounted on a frame 21 at one end of the tube is'a feeder 23 of wellknown type driven by an electric motor 25. rThe material is conductedfrom the feeder by a chute 27 to the hollow trunnion of the tube head 3,and passes therethrough into the primary 'reducing compartment. Itpasses thence through the division plate into the secondary reducingcompartment. The material is delivered from the latter through thehollow trunnion of the tube head 5 to a hopper 29 pigovided with a screwconveyer 31 for conducting the material to the base of an eleva- Thematerial is conveyed by this elevator to an air separator 35, such, forexample, as is disclosed in Letters Patent No. 1,615,- 558, granted inthe name of Thomas J. Sturtevant, J anurary 25, 1927. The fines may beconducted away from the separator by a screw conveyer 37 .at the lowerend thereof,

and the tailings which are rejected may be conducted from the separatorthrough a main chute 39..

A limited stream of tailings may be conducted from the main chutethrough a branch chute 41 which leads to a housing 43 (Fig. 2) extendingover the ball tube mill and having a sump 45 at the base thereof. Thetube of the mill is provided with a pair of scoops 47 which on rotationofthe tube automatically pick up material fIOmfihQ sump and transfer itinto the secondary reducing compartment of the tube.

'To regulate the volume of the limited stream of tailings delivered tothe "secondary compartment, the ehute'is provided with a valve 49 (Fig.4) fast on a shaft 51 mounted in bearings in plates 53 at opposite sidesof the chute. This shaft has an arm 55extending between a pair ofadjusting screws 57 and 59 respectively threaded in lugs 61 and 63 onone of the plates 53, said screws being provided with lock nuts 65 and67. The construction is such that on adjustment of the screws the valve49 may be angularly adjusted and held in the positions desired,

thereby to var the space between the valve and a wall 0,; the chute,andregulate the volume of the limited stream of tailings delivered to thesecondary compartment of the mill.

The main chute has a partition 67 therein dividing the chute intopassages 69 and 71. The passage 69 may be regarded as a part of thebranch chute 41.

Extending from the passage 71 is a branch chute 73 which leads to thefeed chute 27 refiirred to for conducting material to the mil 3 Anytailings in excess of the limited stream flowing through the chute 41 tothe secondary compartment, will accumulate and pile upon the valve 49,and when they reach a suflicient height, they will flow over thepartition 67 and the excess tailings will flow through the passage 71which. may be regarded as a part of the chute 73 and be conducted by thelatter to the feed chute 27, and pass thence to the primary compartmentof the mill.

It is desirable that the excess stream of tailings shall be utilized toregulate the speed of feed of the motor. If the excess stream increases,the speed of the motor should be reduced, but on the other hand, if theexcess stream decreases, the speed of the motor should be increased. Toaccomplish this regulation, in the present instance a valve 75 isprovided in the passage 71, and is fast 011 a shaft 77 mounted inhearings in a box 79 mounted on the main chute. Fast on the shaft is anarm 81 carrying the counterbalance weight 83. Also fast on the shaft isan arm 85. A chain 87 has its upper end connected to this arm, and itslower end connected to a rod 89 passing through holes in supports 91 and93. Mounted on the support 93 is a switch box 95 provided with an arm 97having a fork receiving the rod 89. Nuts 99 and 101 are threaded on thisrod at opposite sides of the fork. The switch in the box 95, in thepresent instance is con structed to provide twospeeds for the motor 25.Since such a switch is understood in the art, it isunnecessary to showand describe the same in detail herein.

In operation, material is fed by the feeder 23 through the chute 27 intothe primary reducing compartment of the mill. The ma.- terial passesthence through the division plate lnto the secondary reducingcompartment of the mill and is delivered therefrom into the hopper 29and conducted by the elevator 33 to the air separator 35, which dividesthe materials into fines and tailings. The fines are conducted by thescrew con- "eyer 37 from the separator. The tailings enter'the mainchute 39. The valve 49 is set to provide the desired limited stream oftaihngs to'pass to the sump 45 and be transferred by the scoops 47 intothe secondary compartment. ThlS limited stream is so regulated thatexcess tailings will not be returned to the secondary compartment andinterfere with eflicient reduction of materials therein. I f tailings inexcess of this limited stream enter the main chute, they will build uponthe valve 49 and flow over the partition 67, and when they build uponthe valve 75, the latter will be rocked in a clockwise direction (Fig.4), and through the chain 87, rod 89 and nut 99 will rock the switch boxarm 97 downward and cause the electric motor to rotate at its lowerspeed, thereby to reduce the amount of meterial fed into the tube mill.\Vhen the excess stream ceases or becomes sufiiciently light, thecounterbalance weight 83 will close the valve 7 5, and through the chain87, rod 89 and nut 101 will rock the switch box arm up and cause theelectric motor to rotate at-its higher speed, thereby to increase theamount of material fed to the mill.

The switch box arm 97 has a small range of movement, and therefore, willbe operated on initial rocking of the valve 75. The provision'of' thechain 87 is desirable in the connections for imparting; movement fromthe valve to the-switch arm, since the chain will permit the valve tomove on to wide open position without effecting {further movement of theswitch arm in case there is sufficient volume of excess material tocause the valve to move to wide open position.

By this invention simple and efiicient means is provided for preventingoverloading of the compartments of the mill, thereby desirablycontrolling the efiicient operation of the mill and enabling anautomatic regulation of the feed which results in uniform fineness inmaterial being ground and maxi* mum output of the mill.

It will be understood thatthe invention is not limitedto the specificembodiment shown, and that various deviations may be "made therefromwithout departingfrom the I spirit and scope of the appended claims.

What is claimed is: J 1. The combination of a' plural compartment millfor reducing -material, means for feeding material to the mill, aseparator for receiving material from the mill, means for from theseparator into streams and delivering the same into differentcompartments of the mill for further reduction, and means operable inresponse to one-of said; streams for controlling the.

feeding means. e v

2. The combination of a plural compartdividing the tailings ment millfor reducing material, means for feeding material to the mill, aseparator for receiving material from the mill, means for delivering alimited stream of tailings from the separator to one of the millcompartments, means for delivering a stream of tailings in excess ofsaid limited stream to another compartment in the mill, and meansoperable in response to variations in the stream of excess tailings forautomatically controlling the feeding means. 3. The combination of aplural compartment mill for reducing material, means including anelectric motor for feeding ma-;

terial to the mill, a separator for receiving material from the-mill,means for deliver-- ing a limited stream of tailings from the separatorto one of the mill compartments, means for delivering a stream oftailings in excess of said limited stream to another compartment of themill, and means operment 'mill for reducing material, a separator forreceiving material from the mill, means for conducting a limited streamof tailings from the separator to one of the compartments of the mill,and means for conducting any tailings in excess of said limited streamto another compartment of the mill, thereby to prevent overloading ofthe mill.

5. The combination of: a plural compartv ment mill for reducing1naterial,,means for feeding material to the m1l'l',a separator forreceivmg materlal from the mill, a chute for conducting a limited streamof tailings from the separator to one of the compartments of the mill, achute for conducting any tailings in excess of said limited stream toanother compartment of the mill, a valve in the latter chute, and meansoperated by said valve for automatically controlling the feeding means.

'6. The combination of a plural compartment mill for reducing material,means including an electric motor for feeding material to the mill, aseparator for receiving material from the mill,a chute for conducting alimited stream of tailings from the separator to one of the compartmentsof the mill,.a chute for conducting any tailings in excess of saidlimited stream to another compartment of the mill, a valve in the lat-[of the mill, means for feeding material to the mill, a separator forreceiving material from the mill, means for conductlng a limitedstream'of tailings from the separator to the sump, means for. conductingany tailin otEer compartment of the mill, and means operated bytheexcess tailings for automatically controlling the feeding means.

-8. The combination ofa plural compartment ball tube mill for reducingmaterial,

- means for feeding material'to the mill, a separatoi' for receivmgmaterial from the mi achute for conducting a limited stream of tailingsfrom the separator to one of the compartments of the mill, a chute forconducting any tailings in excess of said limited stream to anothercompartment .of the mill, valves in said chutes, and means operated bone of said valves for regulating the s cc of the feeding means. I 9. hecombination of a plural compartment mill for reducing material, meansfor s in excess of said limited stream to an- 7 feeding material to themill, a separator for receiving material from the mill, a chute forconducting a limited stream of tailings from the separator to one of thecompartments,

5 a chute for conducting any tailings in excessof said limited-stream toanother compartment, a valve in the latter chute,

and means operated by said valve for controlling the feeding means andhaving provision for increasing the speed on closure of said valve andfor decreasing the speed on opening of said valve.

' WILLIAM T. DOYLE.

